1. Field of Invention
The present invention relates to a communication device, and more particularly to self-powered positioning and modem system for radio/audio communication device, wherein the positioning and modem system is capable of independently sending out positioning data in the form of an audio signal to a control center such that the positioning and modem system supports both the communication provision and the position location provision.
2. Description of Related Arts
Communication devices, such as cellular phone, satellites phone and “Pocket PC”, are considered as one of the common communication tools, wherein a user is able to wirelessly communicate with another user via the communication device via a public network. A communication device generally comprises a microphone speaker and a modem connected with the microphone speaker in such a manner that when the microphone speaker receives an audio signal, the audio signal is encoded to a digital data and sent out in a wireless manner.
Generally speaking, a two-way radio system is considered as one of the most common low-end communication devices, wherein the two-way radio communication system comprises a remote user sending and receiving voice communications to a user at a base station location along a pre-established communications channel. Those communications are half-duplex in nature whereby a user asserts a Push-To-Talk (PTT) switch associated with the radio to transmit a message, otherwise the radio is in receive mode listening for messages when the switch is not asserted. In many scenarios, a detachable corded hand-held microphone unit is used with the radio which the user primarily uses to send and receive voice communications via the radio. The microphone has its own PTT switch which controls the radio transmit/receive mode.
The interface between the radio and the handheld microphone in this scenario typically comprises a PTT signal from microphone unit to radio unit, a mic-audio from microphone unit to radio unit, a speaker audio from radio unit to microphone unit, a round return from microphone unit to radio unit, and a DC Offset voltage from radio unit to microphone unit.
With PTT asserted, the mic-audio signal from the microphone is passed as a baseband signal to the radio which performs conditioning, modulation, and RF signal transmission to complete the transmit steps. With PTT de-asserted, the radio serves to receive the RF signal transmission, demodulate and condition, and then send the baseband signal as speaker audio to the microphone.
Nowadays, the communication devices are incorporated with a Global Positioning System (GPS) for tracking the location of the user, wherein the common GPS generally comprises a built-in GPS receiver equipped with the modem to wirelessly send out a positioning data from the communication device. In order to receive the GPS positioning data, the communication device must employ a processor unit arranged in such a manner that after the processor unit receives the positioning data, the positioning data is decoded to a readable data so that the user is able to locate the position of the sender.
However, such GPS incorporated with the communication device has several drawbacks. The communication device can only transmit both the audio signal and the positioning data wirelessly through the employment of a modem, which may fail should the communication system experiences any technical or power problem.
In addition, existing lower-end radio systems do not support position location provisions, although providing a remote user's position to a base station would be very desirable to enable tracking of the remote user, particularly through the use of the Global Positioning Satellite (GPS) system. Therefore, the GPS must be independently installed to provide positioning data.
For example, while patrolling, police officers or security officers generally must be armed with a radio frequency communication device to keep contact with the control center. For safety and arrangement purpose, their locations are preferred to be tracked by the control center so that the control center can give assistance to them in case of emergency. However, the police officers or the security officers must carry an additional GPS device in order to send out the positioning signal to the control center. In other words, the additional GPS device will increase the load of the police officers or the security officers while patrolling.
As a result, there exists some communication systems with GPS microphone incorporated, wherein the GPS microphone is capable of sending out positioning data to a control center. However, such GPS microphone must be integrated with the communication system such that the configuration of the communication system must be altered to incorporate with such GPS microphone. Therefore, such GPS microphone incorporated communication systems may not be able to provide maximum safety for police or security officers, and as a result, a better positioning system for communication systems must be designed.